Method of making centrifugal pumps



Jan. s, 1935. M B MaCNEILLE 1,986,836

METHOD OF MAKING CENTRIFUGAL PUMPS Filed Jan. 9, 1953 I I INVENTOR. a

5 WQc/K /LLE ATTORNEY,

Patented Jan. 8,

PATENT OFFICE METHOD OF MAKING CEN'I'BIFUGAL PUMPS Martin B. MacNeille, San Francisco, Calif., as-

signor to Fairbanks, Morse & 00., Chicago, Ill.. a corporation of Illinois 1 Application January 9, 1933, Serial No. 650,776

6 Claim.

This invention relates to im rovements in centrifugal pumps and method making same, and more particularly to an improved form of impeller for a small, high speed centrifugal pump 6 intended for use in home water systems, and the system.

like.

Heretofore the pumps generally employed to supply water under pressure to home water systems have been of the more usual reciprocating types, which generally require considerable mounting space. However, centrifugal pumps have been tried, but with little operating success, because of the enormous capacity of even a small pum'p, operating at an economically high speed;'

and where such pumps have been made to deliver a moderate quantity 0 water, sufllcient for domestic requirements, he accomplishment has been at the expense of economical pump speeds,

and, consequently, eflicient pump operation. It is, therefore, an object of the present invention to provide a centrifugal pump impeller and method of forming same, such as to obviate the difflculties above noted.

Another object is attained in an improved centrifugal pump of a particularly rugged build, having few parts, of uniform and easily interchangeable construction, which may be readily incorporated in a simple domestic .water supply A further object is attained in an improved impeller member for a small centrifugal pump, which is constructed of a single piece and adapted to deliver a sumciently small quantity of water, at an economical and efiicient speed of operation, to adapt it for home use.

A still further object is attained in an improved centrifugal pump which is particularly economical in its operation and manufacturing cost, especially as compared with pumps of other principal types, of similar capacity, and which requires only a small mounting space. Yet another object of the invention is attained in an improved centrifugal pump impeller of high speed type, characterized by a low discharge rate, such that the peak torque requirements are minimized, requiring a connected prime mover,

such as a motor, oflower power rating than is as taken along line 2-2 in Fig. 1, and Fig. 3 is a lateralsectional elevation of a pump impeller during an intermediate stage of production.

Referring now to the drawing by numerals of reference, 10 designates generally, a centrifugal pump containing present improvements which will appear as the description proceeds. As shown in Fig. 1, the pump casing is preferably composed of two sections 12 and 14, section 12 including a webbed base bracket or securing member 16, which, as preferred in the present disclosure, is formed integrally with the section, and an extended tubular portion 18, which is provided as a bearing for a pump impeller shaft 20. A, stuflingv box 19 may be provided adjacent the outer end of the tubular portion 18 to prevent leakage along the shaft. The base bracket may be held on a suitable base 22 by any preferred means, such as bolts24. Ribs, or web members 26 are provided, preferably integrally with the pump case section 12, as a means for strengthening the pump assembly. A shouldered seat portion 28, on the periphery of the section .12, receives, in assembly thereon, a peripheral shoulder portion 30 of section 14, the sections being secured together by bolts 31, or by any other suitable means. An extended inlet fitting 32 is preferably formed integrally with the section 14, centrally thereof, and is threaded internally at 34- to receive one end of an inlet pipe 35. A pump volute 36, of usual form, is provided in the peripheral portion of the section 14, and is provided at its outlet end with an outlet pipe fitting or connection 3'7, (Fig. 2).

A novel pump runner or impeller 38, rotatably disposed'withinthe casing formed by the sections 12 and 14, is preferably formed of a single piece of material, such as copper or brass, in the shape of a plate or disc of suitable thickness, as illustrated in Figs. 1 and 2. The impeller is pro vided with an extended hub portion 40, on one side thereof, which, in the present example, is preferably made integrally with the disc, for securing it to one end of the shaft 20, as by a threaded connection. Since the impeller is intended, in operation, to rotate at a relatively high speed, variable according to the size and diameter of impeller, the threaded shaft connection may be made more secure by any of the well known means for accomplishing that result, for example, such as rusting the connection, or providing a lock pin 41 through the hub and shaft. The impeller member is provided with an extended portion 42 on the side opposite the hub 40, and has formed therein an inlet chamber 44, or eye, in line and substantial register with the inlet connection .35. As preferred, the impeller inlet portion 42 may be positioned and partly bearinged on a wear or bearing ring 46, seated against an internal shoulder 47, in a portion of the section 14 adjacent the portion 32. Such a bearing, placed as shown in Fig. 1, will materially aid in decreasing vibration of the impelIer resulting from high speed operation.

One or more centrifugal, thread-like passages 48 are formed in the impeller 38,to conduct water from the inlet chamber 44 to the volute portion 36 of the casing, the peripheral openings of the passages being positioned so as to direct the water flow into the volute, substantially as shown in Fig. l. The passages may be of uniform transverse section, as illustrated, or they may be of a slight conical trend. It will be readily understood that the number and diameter of passages in the impeller is to be determined by the desired quantity of water to be delivered to the water system.

In Fig. 2 of the present example, four such passages are shown, each passage being curved in form, extending substantially radially and having their inner ends tangential to the eye 44, more particularly in Fig. 2, tangential to the circumferential wall surface of the inlet chamber. Further, the diameter of the passages may be-chosen, within the limits of the particular impeller size and thickness, and is to be governed according to the quantity of water to be delivered, and number of passages employed; The impeller passages may be given the predetermined degree of curvature as by drilling or coring the passages radially, or slightly offset from the radii, and tangentially to the eye 44 after the' impeller body is cast or otherwise initially formed. The desired curvature is then imparted by gripping the impeller disc rim in a suitable clamp, the disc then being heated, and the axial portions twisted in the proper direction and to the angular extent to attain the desired curvature of the passages. Fig.

3 illustrates an example of an impeller body prior to its treatment for curving the passages.

The presently noted improvements in the form and construction of an impeller for a small, high speed, centrifugal pump, which adaptthe pump for economical use in a water supply system of low capacity and requirement, presents a de-v cided advantage in manufacture, over those pumps of other types heretofore employed for the same or a similar purpose. The pump impeller, disclosed in detail hereinabove, is so constructed as to eliminate dimculties which have heretofore rendered the very small sizes of centrifugal pumps made without departing from the full intended scope of the invention, as defined in the appended claims.

I claim:

l. The herein described method of constructin a pump impeller which consists in forming a substantially solid disc-like body, in recessing an axial portion of the body to constitute an impeller inlet chamber or eye, in clearing the metal internally of the body to a uniform extent along each of a plurality of-spaced lines from the periphery of the body to the eye, whereby to define a plurality of thread-like passages between the eye andthe periphery of the impeller body, and in relatively displacing the peripheral and axial parts of the body to shape the said passages.

2. The herein described method of forming a cast centrifugal pump impeller, which consists in shaping the passages by angularly displacing 'a part of the solid body element.

4. The herein described method of forming an impeller for a centrifugal pump, which consists,

in forming an impeller body as a substantially solid plate having a central recess, in forming openings in said plate from the periphery thereof to said recess to form a plurality of passages tangentially of the recess, and in subjecting said body to a twisting action todetermine the course of said passages. l

5. The herein described method of forming a centrifugal pump impeller, which consists in drilling a substantially solid plate-like body from a plurality of points toward the periphery to form a plurality of passages of substantially uniform transverse section, in recessing the axial portion of the plate-like body to interconnect the inner ends of said passages, and in angularly displacing the peripheral and axial portions of the body while heated, to determine the trend of the passages.

6. The herein described method 'of forming a centrifugalpump impeller which consists in drilling a substantially solid circular plate-like element from a plurality of points on its periphery, toward its axis to form passages of a general radial trend, and angularly displacing the peripheral and axial portions of the body to impart a curvature to the drilled passages.

MARTIN B. MACNEILLE. 

